although i find it handy to have at least one backup nursery as most nurseries are placed in areas that are built early in the game, forming the core of the colony. it seems that distaster triggers target this part of the colony most often (the general area around your initial starting location and structure factory). having a nursery farther aware from these areas prone to destruction has saved me a number of times. a disaster that strikes the core of the colony usually takes out some important structures so considering that you arent producing new colonists without the nursery, it gets hard to maintain your population long enough to replace the buildings.
TIP:
In colony games, make it a rule of thumb to build another CC and structure factory as you get into higher marks. the starting location is usually slammed pretty hard.
